The advantages, or even the necessity, of harnessing wind energy in historical times as well as in the near future are obvious. Unfortunately, however, the development of wind machines suffered a hiatus in recent decades because of the abundance for a time of very inexpensive oil as an energy source and, concomittently, because of very inexpensive means of distributing the oil, or its resultant energy in other forms, to even the remotest of areas. The acceleration currently of the development of wind machine technology is also apparent and very well understood. What is not as obvious is the very high cost and other disadvantages of harnessing the otherwise free and abundant wind energy by the utilization of prior art approaches. Windmills being considered for development at this time using conventional approaches all suffer at least some of the following, serious disadvantages or limitations: they are unacceptably high in total cost per kilowatt hour when their construction, maintenance, and amortization or replacement costs are considered; they are high in weight per kilowatt of capability; they are vulnerable to storm damage; to optimize aerodynamic efficiency, their rotor tip velocity is very high causing among others, the disadvantage of having a large, hazard radius with respect to catastrophic blade failure; they have a narrow range of wind speed effectivity; and they are unacceptably sensitive to wind direction error, that is, the difference in direction between their heading and the wind vector.
It is an object of the present invention to provide a wind turbine which, by taking advantage of Magnus effect mechanics, avoids all of the above disadvantages.
As pertinent here, the Magnus effect may be considered basically to be that a body spinning rapidly in an environment of moving air, carries with it an envelope or boundary layer of air which is also spinning. On one side of the body the velocity of the boundary air conflicts with the velocity of the moving environment and creates a higher than ambient pressure. On the other side of the body the rapidly spinning boundary air is moving faster than the environment fluid and creates a lower than ambient pressure. The result is a push-pull force toward the low pressure and away from the high pressure side. Thusly did German physicist Gustav Magnus first explain in 1852 the errant cannonball, baseball curving, and the like.
By constructing a windmill having a plurality of coplanar cylinders or barrels provided with adequate spin and attached to a hub rotatable on a horizontal axis parallel to the wind vector, each barrel is push-pulled angularly about the hub axis providing rotational torque energy thereto.
A wind maching using these precepts was invented by Anton Flettner; and a 65 foot diameter Magnus air turbine was operating in 1927 to power a radio station near Berlin. See Flettner's U.S. Pat. Nos. 1,674,169 (filed 1924) and its reissue No. Re. 18,122 (issued 1931). It may be noted that Flettner also invented a Magnus effect sailing ship having two large, vertical, rotating cylinders instead of conventional sails. In 1926, the ship, a small freighter, made its maiden voyage from Germany to New York. By 1927 a three cylinder ship was making a scheduled run between Germany and South America.
These vessels and air turbines provided three pertinent observations; very large and useful transverse Magnus forces are generated; the machines are virtually stormproof; but in their time none of them could compete, for various reasons, with machines utilizing the advantages of cheap oil.
It is another object to provide a Magnus air turbine which is highly cost efficient in power extracted per square foot of intercepted wind.
It is another object to provide such a turbine which is very low in total cost of kilowatt hours generated over the life of the machine.
It is another object to provide such a machine which is very low in total weight per kilowatt generated.
It is another object to provide such a turbine which is stormproof and maintains its efficiency over a wide range of wind velocities including extreme transient gusts.